1. Field of the Invention
The present invention relates to riggers for rowing and sculling boats and, more specifically, to topstays used with riggers.
2. Description of the Related Art
Narrow rowing and sculling boats such as racing shells, are typically equipped with laterally extending riggers used to support oarlocks outboard of the boat hull. Riggers transfer the principle load from the oarlock pin to the boat hull structure. The oarlock pin is fixed rigidly to the rigger, seats the oarlock, and extends generally upward and vertically from the rigger. The load introduced during a rowing stroke causes the rigger and the oarlock pin to deflect. Topstays, which attach typically by means of bolts and nuts at their outer end to the top of the oarlock pin and at their inner end to the boat hull, are commonly used to reduce such undesirable deflection.
The oarlock pins generally can be moved in the lateral direction of the boat to vary the rower's leverage on the oar. In some cases, the oarlock pin can be moved in the longitudinal direction of the boat to change a rower's position front and aft, relative to the oarlock pin. It is also common for oarlock pins to be tilted in the longitudinal direction of the boat and also in the lateral direction of the boat, to set the desired pitch angles for the oar blade as it moves through the water. Because the rigger is a rigid structure and because the position of the oarlock may be adjusted in the manner described, it becomes essential that the topstays, which attach at their outer end to the top of the oarlock pin and attach at their inner end to the boat hull, be adjustable to accommodate the new position of the top end of the oarlock pin relative to the topstay attachment point at the boat hull.
Typically, length-adjustable topstays comprise two tubular members which telescope and are secured with clamps or which are connected with a turnbuckle. In most cases, the outer tubular member connected to the top of the oarlock pin can be rotated around its longitudinal axis relative to the inner tubular member which attaches to the boat hull and thus provides some additional but limited adjustability. Typically, the inner and outer attachment point surfaces of the topstay are created by flattening the corresponding tube ends and by shaping and bending the flattened tube ends to match the mating surfaces at the top end of the oarlock pin and on the boat hull. The manufacturing method to create the flattened tube ends on the topstay is inherently inaccurate and yields topstays which, in the best-case, fit the mating surfaces at the top end of the oarlock pin and the boat hull only for one specific position of the oarlock pin. When the oarlock pin is moved into a position other than this best-case position, the attachment surfaces of the topstay do not match the mating surfaces at the top of the oarlock pin and at the boat hull. When the bolts and nuts are used to attach the topstay to the oarlock pin and the boat hull, unwanted stresses are introduced.
These unwanted stresses can damage the boat hull at the attachment point for the topstay. Further, depending on the boat hull construction, such unwanted stresses can bend and deflect the boat hull and thus cause greater damage and form cracks in the boat hull. In addition, such unwanted stresses bend and deflect the oarlock pin and the rigger, thus changing the desired settings for the oar pitch and increasing the danger of snapping off an oarlock pin.
Conventional topstays have various mechanisms to adjust their lengths which generally fall into two categories. Topstays with a length adjusting mechanism of the first category have one tubular member of the topstay sliding into a larger diameter tubular member of the topstay which has at least two axial cuts at its end so that it can be tightened onto the inner tubular member by means of hose clamps. This simple mechanism relies on friction and there is no guarantee that any length position is positively secured. To overcome this drawback, circumferential grooves are formed on the outer surface of the smaller diameter tubular member for the outer tubular member to bite into when tightened. While this provides a secure length adjustment, the length adjustment is now incremental and not continuous. Topstays with a length adjusting mechanism of the second category have a threaded connection between the two tubular members with the smaller diameter tubular member threading into the larger diameter tubular member. While this provides a simple and secure length adjusting mechanism, the length adjustment can only be done incrementally, one full 360-degree turn at a time. The size of the increment corresponds to the pitch chosen for the thread. To keep the secure length adjustment of a threaded connection but to gain continuous adjustability, it is common to unite the two tubular members of the topstay with a somewhat unwieldy and heavier turnbuckle arrangement.
With their outer attachment point surfaces created by flattening and bending the outer ends of its tubular telescoping members, conventional topstays are typically asymmetric with respect to the side they attach to on the row or sculling boat hull. With port and starboard topstays not interchangeable, additional spare parts are necessary in case a topstay must be replaced.
The present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides a topstay for rowing or sculling boat riggers adjustable in such a way that the surfaces of its outer end and its inner end always match the respective mating surface at the top end of the oarlock pin and at the boat hull, thus eliminating unwanted stresses and the related deformation and damage to the boat hull and the related deformation of the oarlock pin and of the rigger.